This invention relates to an improved catalytic process for decomposing cyclohexyl hydroperoxide in the presence of oxygen to form a mixture containing cyclohexanol and cyclohexanone.
Industrial processes for production of mixtures of cyclohexanol and cyclohexanone from cyclohexane are currently of considerable commercial significance, and are well described in the patent literature. In accordance with typical industrial practice, cyclohexane is oxidized, forming a reaction mixture containing cyclohexyl hydroperoxide (CHHP). The resulting CHHP is decomposed, optionally in the presence of a catalyst, to form a reaction mixture containing cyclohexanol and cyclohexanone. In the industry, such a mixture is known as a K/A (ketone/alcohol) mixture, and can be readily oxidized to produce adipic acid, which is an important reactant in processes for preparing certain condensation polymers, notably polyamides. Due to the large volumes of adipic acid consumed in these and other processes, minor improvements in processes for producing adipic acid and its precursors can provide beneficial cost advantages.
Dougherty, et al., U.S. Pat. No. 2,609,395, disclose a process for oxidation of cycloalkanes to produce cycloalkanols and cycloalkanones, wherein a cycloalkane is reacted with limited quantities of oxygen. The cycloalkane hydroperoxides thereby produced are decomposed by heating in the presence of a cycloalkane, producing cycloalkanols and cycloalkanones.
Gallo, et al., U.S. Pat. No. 2,675,407, disclose optional use of polyvalent metal catalysts in a process for oxidizing cycloalkanes. Specific catalysts disclosed include finely divided metals such as cerium, cobalt, copper, manganese and vanadium, as well as inorganic and organic salts or oxides containing such metals.
Cates, et al., U.S. Pat. No. 2,851,496, disclose a process in which cyclohexane is oxidized with molecular oxygen, optionally in the presence of a catalyst, to provide a mixture containing cyclohexanol, cyclohexanone, and CHHP. According to this process, the resulting CHHP is subsequently decomposed to K and A by heating the mixture in the presence of a bed of solid decomposition catalyst, without adding air or oxygen. Catalysts disclosed by this reference include solid, granular metals or metal oxides deposited upon inert supports. Specific metals disclosed by the Cates patent include iron, cobalt and nickel.
Simon, et al., U.S. Pat. No. 3,093,686, disclose a process for oxidation of cyclohexane to produce mixtures of cyclohexanol and cyclohexanone, wherein oxidation is conducted in the presence of organic acid salts of cobalt, lead, manganese and chromium, which are added to a reactor as solutions in cyclohexane.
Pugi, U.S. Pat. No. 3,530,185, discloses a staged process for oxidizing cyclohexane in which a mixture of gases containing oxygen is introduced to a stream of cyclohexane at a temperature of from 140.degree. C. to 200.degree. C. Optionally, a metal catalyst, e.g., cobalt in the form of a hydrocarbon-soluble compound, is added to the cyclohexane stream.
Constantini, et al., U.S. Pat. No. 3,923,895, disclose a process for decomposing CHHP by heating a solution of CHHP and cyclohexane in the presence of a soluble chromium derivative, which is added to a reactor column as a solution in cyclohexane.
Brunie, et al., U.S. Pat. No. 3,925,316, disclose a method of catalytically decomposing CHHP comprising heating a mixture of CHHP and cyclohexane in the presence of a soluble organic salt or chelated derivative of vanadium, molybdenum, or ruthenium.
Kuessner, et al., U.S. Pat. No. 3,917,708, disclose a process for oxidizing cycloalkanes in the presence of heavy metal salt oxidation catalysts. The anions of the heavy metal salts can be monoalkylphosphate, dialkyl phosphate, monoalkyl sulfate, alkylsulfonic acid, alkylphosphonate or dialkylphosphonate.
Brunie, et al., U.S. Pat. No. 3,927,105, disclose a cascade CHHP decomposition process employing soluble chromium derivatives, including chromium carboxylates and chelated chromium derivatives, which are introduced, in solution, at the base of a reactor column.
Rapoport, et al., U.S. Pat. No. 3,957,876, describe a process for oxidizing cyclohexane in which a cyclohexane-soluble cobalt salt is employed as catalyst. The cobalt salts disclosed include cobalt naphthenate, cobalt octoate, cobalt laurate, cobalt palmitate, cobalt stearate, cobalt linoleate and cobalt acetylacetonate.
Barnette, et al., U.S. Pat. No. 3,987,100, disclose a process for oxidizing cyclohexane in the presence of a binary catalyst system comprising prescribed amounts of cyclohexane-soluble chromium and cobalt salts, wherein CHHP formed during the reaction is decomposed to K and A in the presence of the binary catalyst.
Volpe, et al., U.S. Pat. No. 3,598,869, describe a process wherein cyclohexane is oxidized to form nylon precursors, in the presence of oxygen and a soluble cobalt or chromium catalyst. The step in which cyclohexyl hydroperoxide is decomposed to cyclohexanone and cyclohexanol is not separately discussed.
Wolters, et al., U.S. Pat. No. 3,987,101, discloses a process for producing cycloalkanones and cycloalkanols by decomposing cycloalkyl hydroperoxide in the presence of a solid heterogenous chromium catalyst. However, addition of air or molecular oxygen to a CHHP decomposition mixture is not disclosed or suggested.
Druliner, et al., U.S. Pat. No. 4,326,084, disclose an improved catalytic process for oxidizing cyclohexane to form a reaction mixture containing CHHP, and for subsequently decomposing the resulting CHHP to form a mixture containing K and A. The improvement comprises use of certain transition metal complexes of 1,3-bis(2-pyridylimino)isoindolines as catalysts for cyclohexane oxidation and CHHP decomposition. According to this patent, these catalysts demonstrate longer catalyst life, higher CHHP conversion to K and A, operability at lower temperatures (80.degree.-160.degree. C.), and reduced formation of insoluble metal-containing solids, relative to results obtained with certain cobalt(II) fatty acid salts, e.g., cobalt 2-ethylhexanoate.